make _threadmodule.c clearer, remove unrelated change, add specific test case for openindiana in test_threading.py

Author: jadonduff

Lib/test/test_threading.py

@@ -2241,7 +2241,6 @@ def __init__(self, a, *, b) -> None:
 
         with warnings.catch_warnings(record=True) as warnings_log:
             CustomRLock(1, b=2)
-
         self.assertEqual(warnings_log, [])
 
 class EventTests(lock_tests.EventTests):
@@ -2361,10 +2360,44 @@ def work():
                 thread = threading.Thread(target=work, name=name)
                 thread.start()
                 thread.join()
-                if not name.isascii() and not work_name:
-                    self.skipTest(f"Platform does not support non-ASCII thread names: got empty name for {name!r}")
-                self.assertEqual(work_name, expected,
-                                 f"{len(work_name)=} and {len(expected)=}")
+
+                # Detect if running on OpenIndiana / illumos
+                try:
+                    is_illumos = os.uname().version.startswith('illumos')
+                except AttributeError:
+                    is_illumos = False
+
+                if is_illumos:
+                    # illumos requires ASCII-encoded thread names
+                    if not work_name:
+                        # name didn't get set (set_name may have failed)
+                        self.skipTest(
+                            f"Platform does not support non-ASCII thread names: got empty name for {name!r}"
+                        )
+
+                    work_name_bytes = (
+                        work_name.encode('ascii', errors='ignore')
+                        if isinstance(work_name, str)
+                        else work_name
+                    )
+                    expected_bytes = expected.encode('ascii', errors='ignore')
+
+                    self.assertEqual(
+                        work_name_bytes,
+                        expected_bytes,
+                        f"{len(work_name)=} and {len(expected)=}"
+                    )
+
+                elif not name.isascii() and not work_name:
+                    # Platform does not support non-ASCII thread names
+                    self.skipTest(
+                        f"Platform does not support non-ASCII thread names: got empty name for {name!r}"
+                    )
+
+                else:
+                    # Most platforms
+                    self.assertEqual(work_name, expected,
+                                    f"{len(work_name)=} and {len(expected)=}")
 
     @unittest.skipUnless(hasattr(_thread, 'set_name'), "missing _thread.set_name")
     @unittest.skipUnless(hasattr(_thread, '_get_name'), "missing _thread._get_name")

Modules/_threadmodule.c

@@ -2655,18 +2655,15 @@ _thread_set_name_impl(PyObject *module, PyObject *name_obj)
         return NULL;
     }
 
-    if (rc) {
-        /* If native API refused (EINVAL) and we didn't try ASCII, retry with ASCII. */
-        if (rc == EINVAL && strcmp(encoding, "ascii") != 0) {
-            rc = set_encoded_thread_name(name_obj, "ascii");
-            if (rc == -1 && PyErr_Occurred()) {
-                return NULL;
-            }
-            if (rc == 0) {
-                Py_RETURN_NONE;
-            }
-            /* fall through to raise errno below */
+    /* If native API refused (EINVAL) and we didn't try ASCII, retry with ASCII. */
+    if (rc == EINVAL && strcmp(encoding, "ascii") != 0) {
+        rc = set_encoded_thread_name(name_obj, "ascii");
+        if (rc == -1 && PyErr_Occurred()) {
+            return NULL;
         }
+        /* fall through to raise errno below */
+    }
+    if (rc) {
         errno = rc;
         return PyErr_SetFromErrno(PyExc_OSError);
     }